Physics
Explain with an example that when a liquid evaporates, it takes heat from its surroundings.
Answer
If some alcohol (or spirit) is poured on some cotton (or wool) wrapped around the bulb of a thermometer, the reading of the thermometer falls. The reason for this observation is that, to evaporate, alcohol requires heat which it absorbs from the cotton wrapped around the thermometer (it's surroundings) producing a cooling effect that is recorded by the thermometer as a fall in temperature.
Related Questions
Explain why in hot summer days water remains cool in earthen pots?
Give two applications of evaporation.
A certain quantity of water is heated from 20°C to 100°C. Its temperature is recorded after each 1 minute. The observations are:
Time (in minute) Temperature (in °C) 0 20 1 30 2 40 3 50 4 60 5 70 6 80 7 90 8 100 9 100 10 100 11 100 12 100 What conclusion do you draw from the above table about the boiling point of water? Explain.
Why is cooling produced on evaporation of a liquid?